Yea i totally agree.... Isnt the injen cone by the radiator or somewhere.

 

Some of you guys are forgetting what an engine is basically about. It is at it's raw basics a big AIR pump. The more air you pump in, the more power it puts out (in a nutshell). Air temp changes the density of the air, making it more of it available in each stroke for combustion.

With that said, you have to look at all the talk about "ram" effect, length/restriction of piping, transfer of heat from piping to air, and ambient temp to start with. If you do any extensive research, you will know that vaccum from the engine is what mostly determines the amount of air coming in and doing it's job. In other words, no matter how much you want to argue and try and buy into marketing ploys; simply blowing air across, around, and even thru the filter WILL NOT by itself cause any beneficial gains other than probably eventually lowering ambient temps and thereby eventually making ingested air denser. What I'm trying to say is that air rushing by a filter does not make it have a "ram air" effect as some of you believe. If the engine is not making vaccum, no amount of air blowing by will "ram" anything into the intake. All intakes "suck" air. The only way to make a true ram effect is to make some kind of scoop to basically shove air into the intake, so when the intake valves open there is substantially more air available to swallow.

As for testing differences, I've said this before and noone has yet to show me I'm wrong. Our cars use the ECU to control air/fuel mixtures along with it's other functions. The ECU maps a fuel, spark, timing, etc curve based on sensor readings. One advantage is that it does have some room built in for changes based on these readings. One disadvantage is that it does not always make these changes quickly, but mostly over a period of time. If you take a car to the dyno with a CAI installed, the ECU may have already mapped the fuel/air curve based on that CAI and it's characteristics. If you make a dyno run and then just switch intakes to a pop/hybrid, your ecu will probably still be set for the CAI and thereby giving in-accurate results. One other big problem with dyno testing on the same car is that the pop/hybrid has an unfair advantage with the hood open and the fan blowing cool air across it. That is not the way the intake works on the street. It takes in hot air from the engine bay, without having the benefit of a big fan blowing. The only way that seems fair is by checking vaccum readings (for volume), air temp (for density), and even maybe flow testing (for restrictions and/or volume).

Also, some of you guys seem to ignore the fact that our cars are equiped with those ugly plastic covers under the engine bay. The covers are meant as both shields for road debris and act as a funnel to improve efficiency of air coming in thru the grill, much like a shroud works on non-electrical fanned radiators. I mention this because the injen intake goes down from the TB and has it's filter sitting between the radiator and the tranny/engine. As is also a fact that between the radiator and the engine is one of the hottest places under the hood. Air coming in thru the engine bay (while the hood is closed) is mostly coming in from the grill AFTER it passes thru a hot radiator. I don't see how that would be any more beneficial than the original pop/hybrid. So I personally expect the final real results to be similar to the pop/hybrid setup and not much better if at all.

For my money, I say that the PR CAI (and it's clones) are the best bet. I know that alot of butt dynos have said that it loses steam up top, but honestly most people and most cars for that matter don't spend very much time in that realm. Most of us spend substantially more time accelerating from a stop than do making prolonged triple digit runs. They both have advantages over the crappy stock intake, so props for just changing it at all. I haven't seen any accurate proof that one is better than the other, but common knowledge seems to favor a true CAI over a HAI (in my book).

 

Like I said before, when after 20 minutes of driving, I touched the filter and good 4 inches of piping above it, it's cold.

I put more thought into the whole debate tonight. Honestly, like you said, you'll have to be in the triple digit speed to really tell the difference between PR and Injen. And most of us don't spend a lot of time in that territory so the whole concept of this debate is really kinda an overkill. Many of us probably can only tell the differences between Injen and PR by their sounds. To me, Injen looks better, no cutting holes so that's why I went for that. If people don't mind cutting the hole, then PR is great too.

Tifosi

 

Ok, but think about where it's located. There really is no ambient air that has NOT been heated already. The air that the injen takes in is being heated by the engine AND the radiator. Fans blowing across a hot radiator only net hot air, not cold. Like I was saying before, people seem to think that air going into the intake from under the hood where air is more turbulent and much hotter, not a good thing, is better because it faster moving than the air inside the fender where the CAI is. I disagree because as I said before, anyway you look at it, because ALL the intakes "suck" air in. If it spends most of the time sucking in hot air as opposed to cooler air, I don't see how it can have better gains.

Look at it this way; Most cars for quite some years now are being designed from the factory to pull air into the intake from OUTSIDE the engine bay. Why do you think that is? It takes more time and money to do this. The multi-million dollar R&D depts. would not spend more time and money unless they figured it would work. The problem with those guys is that they have to work w/i restricted guidelines such as emmisions, assembly line headaches, and feasability. It's easier/cheaper for them to make plastic/rubber intakes than to put $200-300 intakes that are more efficient. Their cheap and restrictive ones are the lesser of two evils; better than the old way, but less efficient than the best ones available. They probably end up spending less than $50/ea after it's all said and done. Even in the end, the main point still prevails....why is it that they all try and do the same thing; put in a CAI instead of the cheaper and less trouble to put in HAI of years past???

 

I see how you point of view. Also, the filter on the Injen isn't mainly sucking air it after the radiator, it's sucking air in from underneath as well, which air is cool (hence, that's why when I touched the filter, it was cold) I had a Stillen pop charger before, it lives in a hot environment, everytime I pop the hood and touch the filter, it's hot. If Injen filter lives in constant hot ambient temp as the Stillen as you suggested, then shouldn't the Injen filter be hot just like the Stillen pop charger filter? But in this case, it is not.

Tifosi

 

Eventhough I have only seen pics of the injen intake, I still don't see how it would ingest anything other than hot air because where of where the filter sits. If you have your plastic guards in place under the engine, there is not any air coming from under the car where cooler air would be.

 

Tifosi said plenty of times that the filter is not hot after a drive, so there IS some cool air down there somehow.

 

My two cents:

If you look here, you can see that I have the Place Racing CAI, BUT with a Velocity stack and a LARGE JWT filter. At the velocity stack the filter is about 6", so it's Very big.
http://www.users.voicenet.com/~breaux/car/cai/cai.html

I've since made this a hybrid with the filter relocated in the engine bay, and the upper piping still attached. I did notice two main things.

1. The throttle response of the car seems better. With the CAI, it was almost like the extra piping took the flow of the air longer to respond with the MAF. This could just be in my head, but I have been driving my car for a long time. Whereas now, the velocity stack and filter are attached right up to the MAF.

2. The power loss at higher RPMs is not nearly as noticable with this new setup. With the CAI, my car seemed to drastically lose power at higher RPMs.

As for laminar air flow, isn't that the point of a velocity stack? I'm not sure if all these CAI and Pop systems come with one, but I'm not sure if it really makes much of a difference?

 

The overall throttle response between driving with the OSCAI vs the HKS is night and day, IMO. I ran with a HKS for 1.5 years, then the OSCAI for 6 months, then back to the HKS which I ultimately converted to a hybrid. With the POP/hybrid setup, the accelerator feels much more responsive, especially in 2nd and 3rd gears. I'm sure 4th would feel the same way, but I rarely have any reason to dip into triple digit speeds. When I say responsive, I'm saying the engine seems to spin much more effortlessly. I can only assume the PR CAI and Injen intakes feel a lot like my OSCAI setup. My OSCAI setup was a bit different from other OSCAI setups. I had removed all resonators, ran a midpipe, and cut a 2.5" hole in the driver's side of the airbox to run a 2.5" hose to funnel air from behind the headlight. This setup was about 70% as loud as a POP setup. It flowed well and put down good numbers on the dyno.

Dave

 

If you notice, I never said that he's incorrect, but I did say that it does not make common sense. If you have a filter sucking in air from in between the engine block and the radiator, I don't see how it could ingest anything but HOT air. This is logical when you consider that our cars have plastic covers under neath the engine and a hood above.

 

Actually underneath my filter, it's wide open. There is no plastic cover. I heard someone said that for an auto, there is that plastic cover for the tranny, but I'm 5 spd.

Tifosi

 

As I stated before, unless you construct something similar to what you did simply air rushing by will not help by itself. It looks like you have fabricated something beneficial, so total props go out.

 

I have an auto, hence my comments. I was not aware that you guys have no covers. That may cause better results than previously assumed by me. I still feel that the injen still ingests mostly hot air, except at a stop w/the covers removed, because it still has to "suck" air and the air passing thru underneath the car at speed would require substantial vaccum. All this is off course mostly speculatory and will be until someone has the right equipment, conditions, and results.

 

Actually the velocity stack is provided with the Stillen and JWT Pop chargers. It's the less expensive intakes which just use the MAF adapter that do not come with a velocity stack.

 

I have the plastic shrouds underneath. I've heard of people taking them off, but the should come with the car.

Aren't the intakes (Injen/PRCAI) very similar in length/diameter? If so, the throttle response should be pretty similar, as should the flow. Do the extra bends in the PRCAI plumbing really restrict it?

As for heat, it doesn't seem to make much sense to me. The PRCAI is pretty much away from any heat source. From what I can tell, the Injen plumbing runs right up between the radiator and engine, then over the engine. These are all big sources of heat. So, the plumbing would be more susceptible to heat soaking as far as I can tell.

As for the "top-end" benefits, I don't think that it means top-speed. It means more power at the top of the RPM range. That benefits people at all speeds, and quite frankly, really benefits people who race. I don't know anyone who shifts at 4000 RPMS when racing. I usually stay above 3500 RPMS when racing. I know this has gone from Injen vs. PRCAI to PRCAI vs. every other intake in the world, but are there any differences between the Injen and PRCAI as far as top-end is concerned?

 

For those of you who thinks because Injen sits behind a radiator, that's why it's sucking in hot air, I can understand your train of thoughts. But find yourself a friend who has an Injen and go on a drive and pull on the side of the road, crawl down and touch the air filter to see if it's cold or not. Theory and assumptions in your heads may not be actuality, the best is to find out yourself in person, enough theory talk when you have not experienced in person.

Tifosi

 

Well I think its more the tubing sits behind the radiator and collects heat off of the blow by from the radiator. Yes I used to have an Injen style CAI. Yes I use a Hybrid now.

 

That's the misconception whether the piping gets heate up or the filter.... but in my previous post the page before that I took pics with my temp gun measuring the Injen lower piping, it was at 78 degrees, where pop or HAI or PR piping would sit, it varies from 78 to 87 degrees. So there isn't any difference as far as the piping gets heated up, they all get heat up.

Temp pics: http://litespeed-racing.com/engine-temp/

Tifosi

 

Actually what really needs to be done is someone with the proper equipment measure both intake temps at the throttle body and inside the piping, vaccum measurements, and possibly volume/flow measurements thru the piping of all intakes in question in order to really get accurate results.

Common sense would suggest that if you sit an intake between the radiator and engine block, you will eventually ingest hot air. Maybe w/o plastic covers or after prolonged highway speed driving you will not have a big temp difference in the air around the filter, but until then common sense suggests that hot air is all that is available.

 

You really need to ride in an Injen equipped Max to find out... I own an Injen, after 20 mins of driving, the filter is cold.... end of story. I'll be taking a 3 hr drive next weekend, and I'm pretty sure the result would be the same.

Common sense theory doesn't apply in my case, cause I actually OWN the equipment.

Tifosi

 

I guess laws of physics don't have jurisdiction in your car either? Look, I'm not trying to start a flame war here. I have said it a million times over....any after market intake is better than stock, so props to all that change the crappy stock one. Theory is all that can be commented on because noone has yet done accurate or reliable tests on ANY TWO intakes. I personally opted to go with the PR because in THEORY it does draw air totally away from ANY heat sources thereby POSSIBLY netting better gains. I personally don't believe even PR's claim to 20hp to wheels because I didn't test my car before I put the intake in so I don't know. I do know that it is better than the stock one. Butt and real dynos have confirmed at least that, just not exactly how much more.

If after testing with equipment someone shows that another intake is better than the one I got, I will be one of the first in line to get THAT one. I'm not a PR groupie or salesman, so no skin off my back to throw it in the corner of the garage with the rest of the stock stuff I take off.

BTW, how come some people have commented that the injen probably has less restrictions than the PR when the injen has more bends?

 

Oh no, I never saw it as a flame war, just a friendly debate. But if we are talking about air turbulance in order for my Injen filter to get cool air then we really need an aerodynamist to take my car into a wind tunnel... maybe my Stillen front lip is creating a vortex for air to go into the engine bay from underneath.... maybe there is no calm streamline air underneath our Maximas afterall......god knows. But I agree with you 100%, anything is better than the stock POS intake!

Later.
Tifosi

 

good question...i think they were focusing on the length of the piping. PR CAI is longer which hurts the high end? maybe taht's what they talking about.

As far as reading this thread and doing a little research, here are the strong points i've seen from both sides and why, when i get my new car i may get injen and selling my PR CAI.

INJEN
-Shorter piping allowing less hp taken away at higher rpm's
-DO NOT HAVE TO CUT A HOLE
-In the middle of car so receives a lot more air than PR CAI
*behind radiator so may suck in hot air

PR CAI
-piping located away from engine bay so first air coming in is super cold allowing for best starts
-always sucking in average or cool air
*on the side of car so doesn't get air as easy as INJEN
*have to cut a hole for installation
*longer piping hurts high end performance

through all this, i say if you're going to get a y-pipe, then PR CAI is the best to get because besides cutting the whole, y-pipe normaly kicks in at higher rpms' so the PR's flaw, the y-pipe will take care of so you are now getting best of both worlds. However, i don't want to cut a hole in my next car so i think injen is my best choice....

 

Yeah, 5 speeds have plastic shrouds underneath, but do they cover the whole underbody? Mine doesn't. Goes aout halfway from the front to the tranny or thereabouts.

DW

 

This arguement will never die. Everyone has all of these good points and theories, but no one has undisputable facts. Dyno's are no good, track times are no good.

I don't think that either "CAI" are truely a REAL cold air intake. One pulls stagnent air from the fender and goes through a maze of sharp turns to get to the TB, the other pipes the air through shorter tunnel with the engine beside it.

Truely I think that the Injen is only good if you start the car and start driving, the piping doesn't heat up as much as if you are in city traffic. All the money people put into these products, I'm really wondering why NO BODY has thought of a way to make a Cold Air Box or a hood drop onto a Hybrid. Get the benefits of what a CAI and Hybrids are made to do.

 

I still don't understand why you guys think the PR intake has sooo many twists and turns. It only has ONE turn and it's not like it's a 90 degree turn or anything. The injen has TWO turns. The intake is mandrel bent which means it retains it's diameter throughout the entire length. That's why I don't understand the "restriction" argument. I follow the length issue, but the jury is still out until someone does reliable tests.

 

I agree with you on most points. I still don't see why you would worry about a 3" hole though. If you ever have to put things back to SOTCK, the huge stock airbox more than covers any hole there. Also, the hole is not on the middle of the inner fender, it is almost under the battery box. Trust me, if you put back the car to stock, the combo of airbox and battery tray will not make the hole noticeable at all. It's barely noticeable now with the CAI in place.

 

This is probally a supid question but is my PR CAI a forced induction? Cause on my PR CAI box it says Cold Air Induction. Not intake.

 

Forced induction = SC or Turbo. They literally shove air into the engine.

DW

 

With the Injen intake, I highly doubt when people are talking about it's disadvantage of higher heat, that they are saying that the pipe heats up. That pipe would have to get real hot to heat up the incoming air that is rushing through it so fast.
What they are talking about is the air coming into the intake, touching the metal or filter and seeing that it is still cool doesn't really reflect that the air is going to be less dense when it is heated. As for the air that is accesible (some say that the Injen is better because it sits in front so it should get more air) put a straw where the Injen sits, and one in the wheel well where the PR sits and suck, there is nothing restrictive about the fender well, or advantageous about behind the radiator. Neither is a ram air set up so getting the coolest air is ideal.
I still don't understand the hybrid setup of being more responsive. It loses hp up to 5,000. After 5,000 it does make more power. That is probably good for long 1/4 mile times, but what about short 0-60 sprints. I am not trying to flame on a product here, only to get some questions answered. Here are the dyno's, print them and put them on top of each other, then you'll see what I mean.
http://www.frankencar.com/project_02_max_se.shtml
This is a situation in which the hybrid intake has an unfair advantage, as the hood is probably open with a fan on the engine. yet it still performs poorly at lower RPM.

The only way to truely test an intake is with the engine warmed up, and the good closed. That will show if the denser air in the fender is an advantage even with the extra piping.

As for observing the characteristics of air thats easy. Just get a glass graphix bong, fire it up, and observe that the air moves at the same speed, and is compressed. Whether or not piping is a disadvantage is still up in the air, as piping does compress the air, and possibly smooth out flow, but I would still want the least amount as I could while still getting the coolest air possible. But again I really don't know, the analogy of trying to run with a straw doesn't fit me. Your lungs have a much greater capacity than a straw will allow, that is comparible to the engine but not the intake setup. This is because you still have a throttle body. So with the end of the straw the same size (the part that is in your mouth) will it make a big difference if the rest of the straw where larger, or not their, because you still have that small piece in your mouth causing the restriciton.

Last, the restrictions people talk about at the high end with CAI. Is this top speed or RPM. I would think that the filter would be what is restrictive, unless you have a large throttle body. Your throttle body is the last point of your intake as far as the restrictive piping. Imagine your throttle body is a place that water is being pumped out (by differences in pressure, not forced as a turbo would be.) Would piping be restrictive if it were the same size as the throttle body? I can understand how piping would be if it where smaller than the throttle body, but if you turn up the flow of water won't it only be able to flow as much as the throttle body is able to push out, and since the piping is the same size as the throttle body, wouldn't it be able to handle it since it is proporsional. Does it have more to do with turbulence in the pipe rather than the length? This paragraph is a question, not a statement, I studied human physiology, not engineering. Thanks for any input, or thoughts

 

Intersting comments/theories from all. I have no comment to add as yet since I am still undecided on my opinion (and the wifey is calling me to watch a movie on cable with her). What I do have is a new INJEN intake which was installed yesterday. My first performance mod. I also made sure to Dyno before the install.

See thread: http://forums.maxima.org/showthread....hreadid=158412

 

people say that the longer the piping the less horsepower you will recieve well thats kind of stupid im still sure that my PR CAI is better than stock at high rpm's right? correct me if im wrong.

 

not really true... I think a lot of people tend to forget the most important thing about intakes whether or not they loose a few PEAK hp, when the intake makes their dyno map very even and flat line from 3k rpms to 6k. That provides more overall power than a 2 peak hp at 5600 rpm ever will.

 

Holy smokes Batman!!!!! Someone finally agrees with me???? Thank you Mr. Reeper.

 

Congratulations on the new intake, Injen's look great, and from their dyno's they seem to provide smooth power increases, pretty much across the RPM range. Thanks for sharing your dyno results as well. I was wondering if you could post your dyno sheets.
As another member stated in a few post back, peak hp is not the most accurate way to judge a modification. I agree, and I think peak hp gains is as relevant as hp per liter The reason I want to see your dyno is to see what the characteristics of the gains are across the RPM range. I have posted some links to intakes that gain peak hp, but lose a lot of power else where in the RPM range. This is not ideal for short sprints. I am looking for an intake that increase hp in all ranges, so whether I'm on the highway, or driving 40mph, the hp that I ask for will always be higher than the stock air box. Some will say that intakes don't make that much difference, and arn't a big deal, but the 200 or so dollars that I am going to shell out for one is a big deal to me. So I just want to make sure that 200 dollars will be spent to make my car more powerfull any where in the RPM range, because who knows when you may need that extra power and at what speed.
Thanks again for undertaking the dyno results of the Injen, maybe we'll finally be able to put this one to bed.
Anyone know of a link that has a before and after PR CAI dyno graph, or similar intake like Cattman.

 

Can someone please measure the pipe lengths of the PR and Injen intakes? I'm talking the length from the end of the MAF to where the filter connects. I'm just curious on how much extra piping is really there vs the POP hybrids.

I've been giving a lot of thought to this lately and I'm beginning to think the CAIs probably won't suffer from much of a topend loss compared to a POP/hybrid. The reason I say this is because I've seen some Honda/Toyota CAIs and the pipe lengths are far longer than the Maxima CAIs. We've never been able to prove the power difference between the CAI and POP on the dyno. I'll try and give it a try if WSP will give me the price of the CAI piping.


Dave

 

Toyota and honda usually don't put 14 inch intake runners on their engines either. No flame... I promise.

 

Are you talking about fuel injector runners or the intake plenum itself? No flame either, just wondering.

 

I've said that before too, but noone seems to agree with me.

 

plenum